Conventional semiconductor devices typically are made up of a semiconductor substrate, normally a monocrystalline silicon with a plurality of dielectric and conductive layers formed on it. An integrated circuit (IC) is formed of semiconductor devices connected by a set of spaced-apart conductive lines and associated interconnection lines, such as bus lines, word lines and logic interconnection lines. Such interconnection lines generally constitute a limiting factor in terms of various functional characteristics of the integrated circuit.
Many interconnection lines are copper or copper-based alloys. One drawback of using copper or copper based alloys, for example, is that copper readily diffuses through silicon dioxide, the typical dielectric material employed in the manufacture of semiconductor devices.
A suitable conductive barrier layer is needed between the copper interconnection lines and both the surrounding dielectric and any other metallic contacts it might make. Such a barrier layer can be conveniently formed by employing a material that is substantially impervious to the diffusion of impurities into the copper interconnection lines and to the diffusion of copper atoms into the dielectric or nearby metal contacts. In the copper interconnection processes, conventional tantalum nitride (TaN) is the most commonly used conductive barrier material. The use of TaN requires additional deposition chambers because the deposition of TaN cannot be performed using the same deposition chamber as one with a pure metal. The need for additional deposition chambers for TaN deposition undesirably increases the cost and process complexity for the production of semiconductor devices.